Question

Please answer it and help me​

Answer 1

Answer:

398

Step-by-step explanation:

x+1/x=20

then the hole cube =x^2+1/x^2+2

now hole cube = (20*20)-2 is the answer

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Answer 2

$\\\bigstar\large\;\sf\textcolor{pink}{Given:-}$

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$\qquad\quad\bull\quad\sf{\bigg(x+\dfrac{1}{x}\bigg)=20}$

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Squaring on both sides :-

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$:\implies\sf{\bigg(x+\dfrac{1}{x}\bigg)^2=(20)^2}\\\\\\\\:\implies\sf{x^2+\bigg(\dfrac{1}{x}\bigg)^2+2(x)\bigg(\dfrac{1}{x}\bigg)=400}\\\\\\\\:\implies\sf{x^2+\dfrac{1}{x^2}+2=400}\\\\\\\\:\implies\sf{\bigg(x^2+\dfrac{1}{x^2}\bigg)=400-2}\\\\\\\\:\implies\underline{\boxed{\frak{\textcolor{lavender}{\bigg(x^2+\dfrac{1}{x^2}\bigg)=398}}}}\;\bigstar$

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Identity used :-

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• (a + b)² = a² + b² + 2ab

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